1. Field of the Invention
The present invention relates to a solution treatment method and a solution treatment unit for a substrate.
2. Description of the Related Art
In a photolithography process, for example, in semiconductor device fabrication processes, resist coating treatment for forming a resist film on a surface of a wafer, exposure processing for irradiating and exposing the wafer in a pattern, developing treatment for developing the wafer after the exposure processing, heat treatment and cooling treatment, which are performed before the coating treatment, before and after the exposure processing and after the developing treatment, and so on are performed, and this series of processing is performed in each processing unit provided in a coating and developing treatment system.
In recent years, due to a demand for improved processing capability of the coating and developing treatment system, the need for increasing the number of the resist coating units for performing the resist coating treatment and the developing units for performing the developing treatment as described above disposed in one coating and developing treatment system has been increasing in order to process more of the wafers synchronously.
However, disposing many of the resist coating units and so on requires the coating and developing treatment system to be enlarged and a floor area occupied by the system to be increased. Therefore, it can be proposed that thickness of the resist coating unit and the developing unit is reduced and the developing units and so on are disposed in three tiers or more, which is in more tiers than in a conventional art, in order to prevent the increase in the occupied floor area.
However, disposing these units in multi-tiers in the coating and developing treatment system whose height is limited causes space between the units to be narrow so that maintenance of the units cannot be performed. Even when the maintenance can be performed, the work for the maintenance becomes very difficult. The resist coating unit and the developing unit in particular, which use a treatment solution such as a developing solution, are easy to be contaminated inside the units and need frequent maintenance such as washing, and this is a big disadvantage in disposing the developing units and so on in multi-tiers.
The above developing treatment is usually performed in the developing unit. The developing unit includes a casing, a spin chuck for holding and rotating the wafer placed in the casing, a cup for receiving the developing solution and the like scattered from the wafer due to the rotation of the wafer, and an outside cup disposed outside the cup.
The developing solution is supplied onto the wafer which is delivered into the casing and held on the spin chuck, and thereafter, the wafer is developed for a predetermined period of time in a static state. After the predetermined period of time passes, the wafer is rotated and the wafer is washed and dried.
Furthermore, a supply unit for supplying air into the casing during the developing treatment is provided in an upper part of the casing and an exhaust unit for exhausting an atmosphere inside the outside cup including an atmosphere inside the cup is provided in a lower part of the outside cup.
The air supplied into the casing is normally exhausted from the lower part of the outside cup to form a descendent air current inside the cup, and thereby impurities occurring from the wafer and so on are purged. When the wafer is developed in the static state, however, temperature distribution needs to be maintained uniform over the surface of the wafer, and therefore, the exhausting of the air from the lower part of the outside cup is temporarily interrupted in order to suppress to a minimum the air current on the wafer surface which affects temperature of the wafer.
When the exhausting of the air is thus temporarily interrupted, however, the impurities occurring from the wafer and so on are not appropriately exhausted to float inside the casing and may possibly adhere to the wafer again. When the impurities adhere to the wafer in this way, a flaw in the development is caused with the adhered part left undeveloped. Furthermore, due to the interruption of the exhausting, a flow path of the air supplied into the casing is changed to produce a convection and the like so that uniform temperature distribution over the surface of the wafer is not always obtained. The non-uniform temperature distribution over the surface of the wafer causes difference in developing progresses so that a line width of a circuit pattern to be finally formed may not possibly be made uniform.
The present invention is made in consideration of the above-described aspects and it is a first object of the present invention to appropriately perform maintenance even when solution treatment units such as resist coating units and developing units are disposed in multi-tiers.
Furthermore, it is a second object of the present invention to maintain uniform temperature distribution over a surface of a substrate such as a wafer while preventing impurities from adhering to the substrate again.
In order to achieve the first object, according to one of the aspects of the present invention, the present invention is a solution treatment unit for supplying a treatment solution to a substrate and treating the substrate inside an accommodating vessel, comprising a frame for having the accommodating vessel mounted therein and in which the accommodating vessel is structured to be pulled out freely in a predetermined direction from the frame.
Since the accommodating vessel can be pulled out freely, sufficient work space for performing the maintenance can be secured when the accommodating vessel is pulled out from the frame at the time of the maintenance. Therefore, the maintenance operation can be appropriately performed.
The structure of the frame being pulled out freely is realized, for example, by the structure in which a rail is provided in the frame along the predetermined direction and, for example, the accommodating vessel is movable on the rail.
In order to achieve the second object, according to another aspect of the present invention, the present invention is a solution treatment method for supplying a treatment solution to a substrate and performing solution treatment for the substrate inside a vessel disposed inside a casing, comprising the steps of: supplying gas from an upper part of the vessel inside the casing; adjusting a first flow rate of the supplied gas flowing into the vessel and a second flow rate of the supplied gas flowing out of the vessel; and exhausting the gas flowing into the vessel and the gas flowing out of the vessel outside the casing.
In order to achieve the second object, according to still another aspect of the present invention, the present invention is a solution treatment unit for performing solution treatment for a substrate inside a casing, comprising a vessel provided in the casing to enclose an outer circumference of the substrate; a gas supply section for supplying gas into the casing; an exhaust section for collectively exhausting an atmosphere flowing into the vessel and an atmosphere flowing out of the vessel outside the casing; and an adjusting unit for adjusting a flow rate of gas flowing into the vessel and a flow rate of gas flowing out of the vessel.
According to the present invention, the first flow rate of the gas flowing into the vessel from the upper part and the second flow rate of the gas flowing out of the vessel can be adjusted so that the first flow rate can be increased to strengthen an air current on the periphery of the substrate, for example, when impurities such as a developing solution are likely to occur from the substrate and so on. This makes it possible to appropriately discharge the impurities occurring from the substrate out of the vessel and prevent the impurities from adhering to the substrate again. Furthermore, in order to maintain uniform temperature distribution over a surface of the substrate, the second flow rate is increased to cause the gas from the upper part to flow out of the vessel so that the flow on the surface of the substrate can be weakened. Consequently, non-uniform temperature fall on the surface of the substrate due to the air current is prevented so that the temperature distribution is maintained uniform over the surface of the substrate.